My not so great experience with FPX catalyst insert - Advice?

[clydesdale]

I have an FPX large Hybrid insert. The Cat was replaced after the first year, as it crumbled in the center of the 4 brick rectangular cat. There are a couple potential reasons why. I did check the wood with moisture meter, but sometimes crappy would was used and temps reached about 1 thousand degrees. I remember seeing people here getting 1200-1300 temps on their cats and thought that would be the goal. My manual does not say anything about temps except that the cat gets engaged at 500 or above.
I once again have the center crumbling. I have put nothing but dry wood in this time around. I use wood that is at max 17 on the meter. Most of what goes in is more like 12-14, with some in the single digits. I also keep the stove below 1000 degrees.
The stove comes with a brush to brush the front of the cat to keep it clear. I have come to the conclusion that it is a waste. I took the cat out yesterday and the side bricks were heavily plugged. I vacuumed them out and the cat performs much better. Temps no longer drop at first.
My dealer says it could be from direct flame contact that is causing the degradation of the cat. The problem with that is I don't see how I avoid that. I had the stove backed down 75% and some flames still reached the cat.
I am unimpressed with the Cat life at this time. What to do. Dealer is giving me the impression that they won't warranty. He also has lowered his cat temp max to 850. When I reminded him that the book says nothing about that and he told me 1000 last year, he said he would double check and get back to me.
So, any advice? Thank you.

 

[kennyp2339]

Perhaps your draft is to strong? whats the chimney setup? If your over drafting the flames are going to get sucked up the flue, your internal temps maybe higher than the thermometer reads because again the heat is being sucked up and out.

 

[clydesdale]

Perhaps your draft is to strong? whats the chimney setup? If your over drafting the flames are going to get sucked up the flue, your internal temps maybe higher than the thermometer reads because again the heat is being sucked up and out.

Thanks for the reply.

The stove is mated to 6 inch insulated pipe that is about 30 feet tall. How will I know if the draft is too strong? It does not get constant flame contact, but it absolutely get hit with flame at times when the cat is engaged at first. Do I choke the thing way down first and then engage the cat?

 

[ratsrepus]

30 ft of chimney will do it. Maybe a damper will help, but not sure if a damper can be used on an insert

 

[kennyp2339]

Cat stoves get finicky if the draft is higher that .08" w.c (water column) which is taken during a high fire with a manometer, some stove makers advise not to exceed .05" (BK)

 

[clydesdale]

Cat stoves get finicky if the draft is higher that .08" w.c (water column) which is taken during a high fire with a manometer, some stove makers advise not to exceed .05" (BK)

OK, so do I just back the stove down, take out some air and run it like that? My temps don't seem to high. But, if I open the door to throw another log on when the stove is going well, there is a good draft. But, it is not like every time I open the door I have flames running up the pipe or the pipe is glowing and shaking.
If I need to purchase a new cat, where, aside from dealer? Thanks guys.

 

[Ashful]

I have an FPX large Hybrid insert. The Cat was replaced after the first year, as it crumbled in the center of the 4 brick rectangular cat. There are a couple potential reasons why. I did check the wood with moisture meter, but sometimes crappy would was used and temps reached about 1 thousand degrees. I remember seeing people here getting 1200-1300 temps on their cats and thought that would be the goal. My manual does not say anything about temps except that the cat gets engaged at 500 or above.
I once again have the center crumbling. I have put nothing but dry wood in this time around. I use wood that is at max 17 on the meter. Most of what goes in is more like 12-14, with some in the single digits. I also keep the stove below 1000 degrees.
The stove comes with a brush to brush the front of the cat to keep it clear. I have come to the conclusion that it is a waste. I took the cat out yesterday and the side bricks were heavily plugged. I vacuumed them out and the cat performs much better. Temps no longer drop at first.
My dealer says it could be from direct flame contact that is causing the degradation of the cat. The problem with that is I don't see how I avoid that. I had the stove backed down 75% and some flames still reached the cat.
I am unimpressed with the Cat life at this time. What to do. Dealer is giving me the impression that they won't warranty. He also has lowered his cat temp max to 850. When I reminded him that the book says nothing about that and he told me 1000 last year, he said he would double check and get back to me.
So, any advice? Thank you.

I’m not familiar with that model stove, but I’ve owned five cat stoves of two different models, and can say some designs just have certain issues. What is the model year of this stove, there were a LOT of issues with cat stoves sold in the 1980’s and 1990s, as manufacturers had not really learned all of the ins and outs of managing combustor lifetime.

Max 850 is a ridiculous and completely “made-up” number, I would like to know from where they got that one. At very high temperatures, above 1700F, the metallic coatings on the ceramic begin to flatten out and lose their profile. This results in reduced surface area and effectiveness. As you approach 2000F, they will begin to peel off, and several excursions up to that temperature will destroy the combustor. But you can cruise all day long at your normal 1000F, with zero issues.

Fracturing is caused by thermal shock, essentially unequal forces applied to the ceramic as a result of CTE, and rapidly changing temperature. This usually occurs when people open their door on a hot combustor, the rush of cold air causes stresses. Once, no big deal... but if you do it daily.

Small craters on the inlet side of the combustor is due to flame impingement, google for photos.

More on plugging later, gotta run right now, but tall chimneys can cause fly ash to become airborne, and thus clog the combustor. So can running the combustor too long innactive at beginning of new load, with wet wood.

BTW, if you’re measuring single digit MC%, you’re measuring it wrong. That’s not even possible. Check instructions here on proper procedure.

 

[FPX Dude]

OK, so do I just back the stove down, take out some air and run it like that? My temps don't seem to high. But, if I open the door to throw another log on when the stove is going well, there is a good draft. But, it is not like every time I open the door I have flames running up the pipe or the pipe is glowing and shaking.
If I need to purchase a new cat, where, aside from dealer? Thanks guys.

My initial ceramic lasted about 4 yrs., then I went with Condar Steelcat. I cleaned it last weekend with air compressor and it's still good after 5+ yrs. now, no warping, crumbling, plugging or otherwise.

 

[Ashful]

My initial ceramic lasted about 4 yrs., then I went with Condar Steelcat. I cleaned it last weekend with air compressor and it's still good after 5+ yrs. now, no warping, crumbling, plugging or otherwise.

SteelCats are better at not fracturing due to thermal shock, but they are every bit as susceptible to failure at high temperature due to coating loss or conversion. They’re also more susceptible to ash plugging, due to their much smaller passages.

I just replaced two SteelCats on my two stoves this year, both 3 years old. The stove that had been experiencing ash plugging due to high draft (tall chimney) was converted to ceramic. The other got a new SteelCat, as it has much lower draft (shorter chimney). In both cases, my cat now stays active MUCH longer than it was doing with a 3-year old combustor.

Combustor lifetime is a funny thing, in that damn near every person on this forum who thinks their is running fine, has been amazed at how much better a new one is when they do the swap. This may be one of the most oft-recurring posts on this forum, “I can’t believe how much better the new combustor is, next time I won’t wait so long to change it out.”

 

[weatherguy]

With a strong draft as yours you may want to get a steel cat, it will plug but if it's easily accessible to clean it's no problem. The best thing to do is try to rig up a damper to slow your draft down, cat stoves dont do as well with a strong draft. I have a strong draft with a steel cat, every 2-3 weeks I take it out clean it and I'm up and running, takes all of 10 minutes.

 

[edyit]

But, if I open the door to throw another log on when the stove is going well

are you bypassing the cat when you do this? opening the door to throw on another log could be what is causing shock? just throwing out a guess here

 

[jetsam]

Condar (a cat vendor) recommends that you not exceed 1500°F with their cats. I am not sure that trying to keep it below 850 is going to be good for heat output. 1500 is already a conservative number with a 10% margin for error built in.

I've never seen your stove, but it sounds like maybe it has a design issue that allows direct flame impingement of the combustor. Maybe you could fab a flame deflector for it.

 

[Woodsplitter67]

Onot like every time I open the door I have flames running up the pipe or the pipe is glowing and shaking.
.

Thats not verry good, your drafting to hard. I dont know if you can drop your stack a little shorter, but if you can maybe shorten it up. Maybe speak to the dealer or get them out there and show them whats going on..

 

[webby3650]

Condar (a cat vendor) recommends that you not exceed 1500°F with their cats. I am not sure that trying to keep it below 850 is going to be good for heat output. 1500 is already a conservative number with a 10% margin for error built in.

I've never seen your stove, but it sounds like maybe it has a design issue that allows direct flame impingement of the combustor. Maybe you could fab a flame deflector for it.

Lopi doesn’t use a flame shield in any of their stoves. I could literally see flames shooting straight thru the cat on my Cape cod, there’s nothing you can do to prevent it. Premature cat failure is imminent with these stoves if you ask me.

 

[Ashful]

With a strong draft as yours you may want to get a steel cat, it will plug but if it's easily accessible to clean it's no problem.

I’d have recommended the exact opposite, why are you saying steel cat? The only reason I switched one of my Ashfords to ceramic is because steel cats are so easily plugged under high draft. Ceramic cats don’t seem as susceptible to this.

A key damper is the solution to the ash plugging, as well as his glowing pipe during bypass operation.

Still interested to know his procedure on bypassing cat before opening door to load wood.

 

[clydesdale]

I always bypass the cat when loading. If I don't, I get smokey smell in the house. I think some may have misread one of my post. I wrote that it is NOT like I the pipe glowing or shaking. I personally don't think the draft is a big issue. But, the cat was certainly clogged. The brush is junk. This thing needs periodic vacuuming. The stove is performing much better since cleaning the cat. I still keep the cat temps in the 800-950 zone. To do this, I run with air control about 70% choked down. How much do not cats cost? My dealer is saying that I would have to buy this one. I am not pleased with that, as the stove is starting it's third season. The cats have a 6yr warranty. How much do they cost and where can I get a replacement? Thanks

 

[Ashful]

I always bypass the cat when loading. If I don't, I get smokey smell in the house. I think some may have misread one of my post. I wrote that it is NOT like I the pipe glowing or shaking. I personally don't think the draft is a big issue. But, the cat was certainly clogged. The brush is junk. This thing needs periodic vacuuming. The stove is performing much better since cleaning the cat. I still keep the cat temps in the 800-950 zone. To do this, I run with air control about 70% choked down. How much do not cats cost? My dealer is saying that I would have to buy this one. I am not pleased with that, as the stove is starting it's third season. The cats have a 6yr warranty. How much do they cost and where can I get a replacement? Thanks

New cats usually run $150 - $300, depending on stove model.

There are only a few things that can clog a cat, so we should be able to figure this out:

1. Extremely high temperature can cause a steelcat to distort and act as if it is clogged, but you have a ceramic cat, so this isn't an issue.

2. Fly ash becoming airborne and getting sucked into the combustor. This is usually caused by too-high draft.

3. Plugging with creosote can happen when you engage too early, or stall it too often, causing creosote to build up in an inactive combustor.

That's really about it. Knowing you have a 30 foot pipe on that thing, why do you think draft is not the issue? Have you put a manometer on it while running full-bore?

 

[wooduser]

I must say that I admire the process of diagnosing issues brought up by this poster, and possible solutions.

That's not easy to do when you haven't even had a chance to examine the equipment or view its operation.

Very impressive!

 

[wooduser]

I have an FPX large Hybrid insert.

Which particular model do you have? I can't identify the insert with the information you supply. I'm interested in looking at the warrenty and the installation instructions to see what they say about properly installing the equipment and liability for defects or incorrect installation.

 

[weatherguy]

I’d have recommended the exact opposite, why are you saying steel cat? The only reason I switched one of my Ashfords to ceramic is because steel cats are so easily plugged under high draft. Ceramic cats don’t seem as susceptible to this.

A key damper is the solution to the ash plugging, as well as his glowing pipe during bypass operation.

Still interested to know his procedure on bypassing cat before opening door to load wood.

You can clean a steel cat and it wont crumble. I also suggested a damper. I have a strong draft and would prefer to vacuum it once a month than replace a crumbling ceramic cat, been there, done that.

 

[weatherguy]

I always bypass the cat when loading. If I don't, I get smokey smell in the house. I think some may have misread one of my post. I wrote that it is NOT like I the pipe glowing or shaking. I personally don't think the draft is a big issue. But, the cat was certainly clogged. The brush is junk. This thing needs periodic vacuuming. The stove is performing much better since cleaning the cat. I still keep the cat temps in the 800-950 zone. To do this, I run with air control about 70% choked down. How much do not cats cost? My dealer is saying that I would have to buy this one. I am not pleased with that, as the stove is starting it's third season. The cats have a 6yr warranty. How much do they cost and where can I get a replacement? Thanks

6 year warranty but hours is the more important figure. For some the hours can last 6 years, for others 3 years. Try firecat, it's not a big expense compared to the wood your saving with a cat stove.

 

[clydesdale]

I have the Fireplace xtrordinair large hybrid fire insert. I run the thing all winter. I use it as the main heat source. It is on now and I will have coals waiting for me 8-9 hrs later. I then open the cat, open the air and start it back up. After about 1/2 hr or so and the temps are back up to 600+, I engage the cat. The cat will then stay engaged until I reload.
When I took the cat out, I shined a flash light from behind and it was only visible in the middle. I then vacuumed that cat and had to mildly agitate with the brush that came with the stove. When I put it back in, it performs much better. But, the center is hurting and crumbled. So, do I just vacuum the thing in place every few days and remove it mid season and do a full vacuum? Where can I purchase one of these aside from my dealer.

 

[Ashful]

When I took the cat out, I shined a flash light from behind and it was only visible in the middle. I then vacuumed that cat and had to mildly agitate with the brush that came with the stove. When I put it back in, it performs much better. But, the center is hurting and crumbled. So, do I just vacuum the thing in place every few days and remove it mid season and do a full vacuum? Where can I purchase one of these aside from my dealer.

Does the material causing the clogging appear to be light white fly ash, or dark creosote?

If you can vacuum in-place, and there’s not an issue sucking crap into the back of it from the chamber beyond, then go for it!

Crumbling that goes straight through the combustor is usually a sign of thermal shock, whereas flame impingement on an already-hot combustor usually only causes cratering on the surface. I guess anything is possible, like flame impinging on an otherwise-cold combustor after freshly loading causing thermal shock, but this is how they are normally presented. That’s not to say you’re doing anything wrong, either way, it could just be an issue with the design of that stove. It would be good if we could get some others with experience on your specific stove to comment.

@begreen, could you add the stove model to the thread title? It might help to get a more targeted response.

 

[jetsam]

...it could just be an issue with the design of that stove. It would be good if we could get some others with experience on your specific stove to comment.

Lopi doesn’t use a flame shield in any of their stoves. I could literally see flames shooting straight thru the cat on my Cape cod, there’s nothing you can do to prevent it. Premature cat failure is imminent with these stoves if you ask me.

 

[Woody Stover]

It does not get constant flame contact, but it absolutely get hit with flame at times when the cat is engaged at first. Do I choke the thing way down first and then engage the cat?

Flames can't hit the cat in my stove in any event but I still like to slow the fire a bit before closing the bypass. Once the stove is up to temp, I cut the air and let the flame settle down for a couple minutes, then flip the lever.